This invention relates to two or more hydraulic machines which are connected with each other through branch water manifold which are branched upstream and/or downstream of the machines, and more particulary to an operation-control method for hydraulic machines which method controls or limits operational interaction of respective hydraulic machines and prevents an abnormal hydraulic-pressure condition in water conduits.
Recently, there have been constructed many manifold type hydraulic power plants from viewpoint of economy of civil engineering works, in which a water conduit is branched into branch water conduits with each hydraulic machine being located in each branch conduit. In a power plant of the type described, respective hydraulic machines are mutually affected in terms of hydraulic pressure through branch conduits. According to the conventional method for controlling the operations of hydraulic machines, machines are independently controlled. Accordingly, the operation control for one hydraulic machine is independent of a change in an operational condition of the other machines, so that an optimum control is not conducted for prevention of influence of the pressure of one water conduit on the other or for prevention of a resulting transient change in the operational condition of the machine. To overcome this shortcoming, it may be one of solutions to feed a change in the operation condition of one hydraulic machine to the other to control the operational condition thereof. The Japanese Laid-open Patent Publication No. TOKUKAISHO 47-16831 teaches a method for controlling guide vane openings to prevent an instable operation of one hydraulic machine, which is caused due to a change in operational condition of the other. However, there has not been proposed a method for controlling the operational speed of guide vanes, which most affects a transient hydraulic-pressure change in water conduits.